Axial pump



Oct'. 5, 1937. F. BURGHAUSER AXIAL PUMP x Filed March 18, 1956 Patented Oct.' 5, 1937 UNITED STATES,

lPATE-N1# OFFICE l AXIAL PUMP Franz Burghauser, Nuremberg-S., Germany Application Maren 1s, 1936, serial No.v 69,552 t f In Germany March 14, 1935 s e claims. (ci. s-12s)- to be reduced as desired at the casing surround--v l0 ing the screw spindles. Moreover, means are also provided to prevent further frictions.

Inthe accompanying drawing Figs. 1-3 show a screwfor axial pump of known construction.

Fig. 1 is a longitudinal section through the pump,

Fig. 2 is a cross section, on an enlarged scale,

through the screw prole and'a portion 'of the casing surrounding the screw spindles, and Fig.

3 shows a longitudinal section ,throughthe pump in a plane at a right angle to that of Fig. 1. e The main spindle I 'and the auxiliary vspindle 2 are guided in the two bearing covers 3 and 4 and `surrounded by the casing 5. The two spindles I e,

and 2 are positively and rotatably connected together bythe two gearwheels 5 and'1.

Figs. 4-6 of the drawing show a screw pump having reduced friction losses according to vthe invention. .-First of all the profile of the screw thread according to the known construction and shown in Fig. 2 is to be compared with that of the present invention and shown in Fig. 5,

whereas according to the construction shown in Fig. 2 the portions of the peripheries of the spindles I and 2 which slide upon the casing 5 to-4 gether correspond about to the periphery of one spindle, .According to thepresent invention and V as shown in'` Fig. 5 portions of the peripheries of the spindles are reduced in diameter as desired to permit but small portions of the pepheries of the spindles to slide upon the casing 5, 'whereby 40 the surface friction' between vthe spindles and the casing may be reduced as. far as desired.

The novel screw prole according toFlg. 5f

consists of a cylinder 8, carrying a. thread comb 9 near which a thread notch I0 is provided. The width of the circumference of the threadcomb aand'of the thread notch I0 may-be equal or different from each other, depending upon the desired distribution of the work upon the main and the auxiliary spindle. y

Two turns of the thread of the spindles are suilicient for a complete tightening if the ank Il of the thread is backed off. AThe flanks I2 and I3 of the thread may be of any shape and may be soeformed also, that they may serve for y: transmitting power from the main Yspindle upon thel auxiliary spindle, for instance' according to an evolvent. Also the diameter of the cylindery 8 of the main spindle may be different from that of the cylinder` I@ of the auxiliary spindle, tp obtain a ratio of gearing for the purpose of adapt-.- 5 ing the auxiliary spindle to a certain number revolutions of the main spindle.

The spindles I and '2 may also be provided witha plurality oflthread combs 9 and thread notches I0 and also a. plurality of auxiliaryspindles 210 `may be arranged around the main spindle I.

A further reduction of the surface frictionis obtained according to the present invention by a particular construction of the' bearings which serve to compensate for the axial thrust of the 15 liquid upon the spindles.

To compensate for this axial thrust of the liquid on the front faces of the bearings I5, i5 and I6, I6 in the construction shown in. Fig. 1, a certain diameter of the bearings was required 20 hitherto and owing to the fact that-these bearings vsin-lultaneou'sly were designed to serve as supports, a certain length also was required which could not be neglected. Due to this fact, in most v cases unsufilciently loaded bearings of great sur- 253 face friction resulted. e

According to the construction of the invention shown invFig. 5,*the diameter and the length'of the bearings I1, I1 andy I8, Ilare reduced to such an extent' as tol obtain normally -loaded 30 bearings, whereby the surface friction also is correspondingly reduced. For the purpose of axial compensation of thethrust of the liquid upon the spindles, -each bearing I1,l I1 and I8, I8 f is provided with a correspondingly dimensioned 35 thrust compensating piston I9, .I9 and 20, 20 whichvtogether with the front faces of the bear- 1 ing pivots compensate theaxial thrust of liquid. The lower bearings I1, I1 and the compensating pistons I9, I9 are loaded by the liquid pressure 4o prevailing in the pressure chamber V2| of the pump by way of the port 22 of the spindle I and .by way of notchesl 23, 23 provided in the bearings I1, I1 respectively.

/ One face of each of theupper release pistons 45A 20, 25| is subjected to the liquid pressure prevail- `ing in the pressure chamber 2 I and the other face port 25 ofthe spindle 2, to the pressure ofy the 50 suction chamber respectively. By providing separated bearings and compensating pistons on each spindle, a substantial reduction of the bearaing friction is obtained, because with a reduc-l tion of the diameters of the bearings, the friction is reduced by the square of the diameters.

A further reduction of the surface friction between the outer peripheries of the spindles and the casing is, according to the present invention, obtained by the fact, that portions of the casing, directly surrounding the spindles and not required for tightening purposes, are cut away, so

` that, as shown in Fig. 6, the casing is cut away along helical lines 26, 26 and 21, 21 at the ends at which the spindles enter and leave the casing respectively. For the sake of simplicityr the casing may also be cut away along planes 26, 26 and 21, 2l.

In operation, iluid is drawninto the pump through the port 30, is received in the suction chamber 3|, is drawn into the pockets formed by the interengaging thread combs 9 and forced by the rotation of the spindlesupwardly in to the pressure chamber 2l from which it is discharged through the outlet port 32. Not only is dead surface friction prevented hereby, but also the flow of.the,liquid into the screw spindles is substantially facilitated.

What I claim isz- 1. An axial or screw pump, comprising a casing, bearings mounted in said casing, interengaging screw spindles of cylindrical lcross section journalled in said bearings, a thread comb provided on the cylindrical portion of said spindles near which a thread notch is cut into said portion, a compensating piston mounted adjacent each bearing of each of said spindles, a casing portion surrounding said spindles, means for supplying compensating fluid pressure to said pistons, and said pistons together with said bearings compensating for the thrust of the liquid upon said spindles.

2. An axial or screw pump, comprising a casing, bearings mounted in said casing, interengaging screw spindles` `of cylindrical cross section joumalled in said bearings, at least one thread comb provided upon each of the cylindrical portions` of said spindles near each of which a thread notch is cut into said portions, a compensating piston mounted adjacent each bearing of each of said spindles, means for supplying compensating fluid pressure toA said pistons, a casing portion surrounding said spindles, and said pistons together with said bearings compensating for the thrust oi' the liquid upon said spindles.

3. An axial or screw pump comprising a casing, at least two interengaging screw spindles rotatably mounted therein, bearings formed in each end of said casing and providingmounts for said spindles, individual and intercommunicating pressure chambers fo'r each vend of each spindle formed in the ends'of saidcasing adjacent said bearings, said spindlesvbeing formed to provide means for supplying fluid pressure to said chambers, and compensating pistonsformedon said spindles adjacent both ends thereof and working in said pressure chambers to provide a pressure balance for said spindles.,

FRANZ BURGHAU'SER. 

